A judge's decision to block a $20 million lawsuit settlement has been applauded — by one of the plaintiffs in line for the payout.

Stephen MacGillivray is one of hundreds of Canadian patients who took the class action lawsuit against the drugmaker Purdue Pharma (Canada), over how the company marketed the painkiller Oxycontin.

"Purdue Pharma knew this drug was addictive, and they blatantly told people that it was not," he told The Current's Anna Maria Tremonti.

"They were basically lying to the doctors."

MacGillivray was prescribed the painkiller after a workplace accident in 1997. He said he became addicted within two months, and over the next decade of dependence he lost his job, his family, and ended up with a criminal record.

I became addicted in just two months, Stephen MacGillivray tells Anna Maria Tremonti. 1:40

The $20 million settlement had already been signed off by judges in three provinces.

Part of the judge's reasoning was that "the proposed settlement was not fair, reasonable or in the best interests of the class as a whole," according to Matthew Herder, director of the Health Law Institute at Dalhousie University.

Once $2 million of the $20 million sum had been set aside for the provinces, plaintiffs would have received $11,000 to $13,000 each.

"Purdue Pharma (Canada) has always marketed its products in line with the Health Canada-approved product monograph and in compliance with all relevant rules, regulations and codes, including the Food and Drugs Act," the company told The Current in a statement. Purdue Pharma have never made an admission of liability in the case.

A judge recently rejected a settlement in a decade-long lawsuit over how Purdue Pharma (Canada) marketed and sold its pain medication OxyContin. (Toby Talbot/Associated Press)

The rejection now creates an opportunity to review the options available to both patients and provincial governments, said Herder.

"I think part of the real value of this moment in the middle of this class action is to have a more public conversation about the different legal mechanisms that might be available."

Matthew Herder explains the legal differences between the jurisdictions, and what options are open to Canada. 1:28

He added that if provincial governments decide to follow Justice Barrington-Foote's move away from supporting the class action, they could "try and recover a greater measure of money to deal with the public health crisis."